Arc lamps have long been used to provide a high intensity beam of light for use in a projection display system. Many of the projection display systems in use today, whether a traditional theater movie projectors or a micromirror based conference room projector, use an arc lamp as a light source. Arc lamps provide a high intensity light beam with a color spectrum suitable for image projection in a relatively small package.
Some arc lamps use an alternating current supply to drive the lamp. Changes in the polarity of the drive current create fluctuations in the intensity of the light generated by the light source. These fluctuations are not a concern for most types of displays. The fluctuations, however, degrade the projected image when they occur only during a portion of an image created by binary pulse width modulation (PWM). In order to use an arc lamp, binary PWM display systems must be synchronized to the fluctuations. Synchronizing the display system to the arc lamp increases the cost of the system and often reduces the brightness of the display system.